JPH06179306A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce the weight of a tire without impairing the durability and the air pressure maintaining capability thereof in constituting a carcass cord of a polyester cord. CONSTITUTION:Regarding a pneumatic tire having an inner liner layer 3 laid inside a carcass layer 1, a distance from the carcass cord 1c of the carcass layer 1 to the inner liner layer 3 is kept between 0.1mm and 0.6mm. In addition, the carcass cord 1c is made of a polyester cord having a thermal shrinkage factor between 0% and 1.0% at 140 deg.C, a thermal shrinkage force equal to or less than 0.11g/d at 140 deg.C and an intermediate ductility equal to or above 4.0% with a thermal shrinkage force of 2.25g/d at a room temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire that can be reduced in weight without impairing tire durability and air pressure retention, and more particularly to a tubeless pneumatic tire for passenger cars.

[0002]

2. Description of the Related Art Further reduction in fuel consumption of automobiles is required as a measure to protect the environment of the earth, and as a part thereof, weight reduction of pneumatic tires is strongly demanded. As a measure for reducing the weight of the pneumatic tire, reducing the thickness of the carcass layer from the carcass cord to the inner liner layer is one effective means.

Generally, in tubeless pneumatic radial tires for passenger cars, polyester cords are often used for carcass cords, and rubber having a high air permeability such as butyl rubber is used for the inner liner layer inside the tires. Trying to hold. The air pressure retention of the inner liner layer largely depends on the rubber thickness, and the thinner the rubber thickness is, the lower the air pressure retention becomes. Therefore, it is necessary to maintain the air pressure above a certain level.

However, since the polyester cord has a heat shrinkability, as shown in FIG. 2, the carcass layer 1, the tie rubber layer 2 and the inner liner layer 3 of the green tire before vulcanization have uniform thicknesses A, Even if it has B and C, the carcass cord 1c contracts due to the heating during vulcanization, and the rubber of the inner liner layer 3 or the like is wavy in an uneven shape, and the carcass cords 1c have convex portions b between them. By cutting in, a thin portion a having a thickness Cm is formed in the inner liner layer 3, and air leakage easily occurs from there. Further, since the inner liner rubber or the like cuts in between the carcass cords 1c, the amount of coat rubber around the cords is reduced and the carcass cords 1c are easily separated,
Tire durability deteriorates.

For this reason, conventionally, the carcass layer 1 is made thicker, the thickness is made uneven, or the tie rubber layer 2 is inserted to prevent the inner liner layer 3 from biting. Specifically, the dimension D from the carcass cord 1c to the inner liner layer 3 needs to be 0.70 mm or more, and it is difficult to reduce the weight of the pneumatic tire by making it thinner than this.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic tire which, when the carcass cord is composed of polyester cord, can be made lightweight without impairing tire durability and air pressure retention. is there.

[0007]

The pneumatic tire of the present invention which achieves the above object is a pneumatic tire in which an inner liner layer is arranged inside a carcass layer, wherein the carcass cord of the carcass layer extends from the inner liner layer. To 0.1 to 0.6 mm, and the carcass cord has a heat shrinkage ratio at 140 ° C. of 0 to 1.0%, 1
Heat shrinkage force at 40 ° C. is 0.11 g / d or less, and room temperature is 2.
It is characterized by being composed of a polyester cord having an intermediate elongation at 25 g / D of 4.0% or more.

By using the ultra-low shrinkage polyester cord as the carcass cord, the dimension from the carcass cord to the inner liner layer is 0.6 m.
Even if the thickness is less than m, it is possible to prevent the inner liner layer from penetrating between the carcass cords due to the heat shrinkage of the carcass cords during vulcanization molding, thus reducing the weight of the tire and impairing the tire durability and air pressure retention. Can be achieved without.

In the present invention, the heat shrinkage ratio and the heat shrinkage force are the change in yarn length and the heat when the temperature is increased from room temperature to 140 ° C. at a rate of 5 ° C./min from a load of 20 g per denier. It is a value obtained from the contraction stress. Also,
Intermediate elongation is 2.25g per denier at room temperature
It is a value obtained from the change in the yarn length when the load is applied. Hereinafter, the present invention will be specifically described with reference to the drawings.

In the pneumatic tire shown in FIG. 1, the carcass layer 1 is spanned from the tread portion 5 to the left and right sidewall portions 6 and the bead portion 7. Both ends of the carcass layer 1 are respectively folded around the bead cores 8 of the left and right bead portions 7 from the tire inner side to the outer side. 9 is a belt layer, and 10 is a belt cover layer. Figure 2
As will be shown in detail, an inner liner layer 3 is laminated inside the carcass layer 1 with a tie rubber layer 2 interposed therebetween. An ultra-low shrinkage polyester cord is used for the carcass cord 1c, and as a characteristic of the polyester cord before tire vulcanization, a heat shrinkage ratio at 140 ° C. is 0 to 0.
1.0%, the heat shrinkage at 140 ° C is 0.11
Those having an intermediate elongation of 4.0% or more at room temperature under 2.25 g / D are used.

In the laminated structure from the carcass layer 1 to the inner liner layer 3, the dimension D from the carcass cord 1c to the inner liner layer 3 is 0.1 to 0.6 m.
It is regulated to an extremely thin state of m so as to contribute to the weight reduction of the tire. In this laminated structure, the tie rubber layer 2 inserted between the carcass layer 1 and the inner liner layer 3 is not always necessary and may be omitted depending on the situation.

In the pneumatic tire having the above structure, since the carcass cord 1c has an extremely low shrinkage, the heat shrinkage during vulcanization molding is extremely small, and the dimension D from the carcass cord 1c to the inner liner layer 3 is 0. Even if the thickness is 1 to 0.6 mm, it is possible to suppress the phenomenon of the inner liner layer 3 biting into the space between the carcass cords 1c.
Therefore, a thin portion is not generated in the inner liner rubber layer 3 to reduce the air pressure retention property, or the tire durability is not reduced due to the inner liner layer 3 being cut into the carcass cord. Moreover, the dimension D is 0.
It is possible to reduce the weight of the tire by making the thickness extremely thin to 6 mm or less.

The polyester cord used in the present invention is
It is desirable to use polyethylene terephthalate as a main component, and as a yarn forming condition, from a shrinkage-oriented partially oriented yarn (POY) which is lower than that of a conventional high stress spinning yarn obtained by spinning at a higher stress than ever before. It is desirable to manufacture. The number of twists of this polyester cord is not particularly limited,
Conventional polyester tire cords are applied. In addition, the twisted polyester cord is treated with an adhesive having reactivity or an adhesive having a high affinity with polyester in the same manner as in the prior art, and then treated with RF.
It is possible to perform a two-step process in which L is used. As the reactive adhesive, for example, an epoxy adhesive or a blocked isocyanate adhesive can be used. As the adhesive having a high affinity with polyester, for example, a chlorophenol derivative adhesive ( "Barca Bond" E
Etc.) can be used.

[0014]

[Examples] Tire size is 185 / 70R13, total denier is 1500D / 2, twist is 40x40, inner liner layer thickness C is 0.40 mm, and polyester cord is used as a carcass cord. The tires 1 and 2 of the present invention in which the fiber characteristics of the carcass cord, the thickness A of the carcass layer, the thickness B of the tie rubber layer, and the dimension D from the carcass cord to the inner liner rubber layer are different as shown in Table 1, respectively. Conventional tires and comparative tires 1 and 2 were manufactured.

The tire 2 of the present invention is the tire 1 of the present invention.
The tire having the same configuration except that the tie rubber layer is omitted and the coat rubber of the carcass layer is thickened and has an uneven thickness. Table 1 shows the results of evaluating the tire durability and the weight reduction index of these five types of tires by the following methods.

Tire durability : Air pressure 2.4 kg / c according to the certified extended fracture test of FMV # 109 high speed performance test.
Assemble the m ² test tire on the rim of 13 × 5J, and
Under a load of 45 kg, the vehicle first started traveling at a speed of 81 km / hr, and after traveling for 2 hours, the speed was 121 km / hr.
The tire durability was defined as the speed at which the tire was broken by increasing the speed to 8 hr / hr and then increasing the speed by 8 km / hr every 30 minutes. Measured values of conventional tires are the standard (100)
It is displayed with the index. The larger this index, the better the tire durability.

Weight reduction index : Based on the weight of a conventional tire (1
00). The smaller the index, the smaller the tire weight. It can be seen from Table 1 that the tires 1 and 2 of the present invention are lighter while possessing tire durability superior to that of the conventional tire.

[0018]

According to the present invention, the dimension D from the carcass coat to the inner liner layer is made as thin as 0.1 to 0.6 mm, while the carcass cord is made of ultra-low shrinkage polyester cord. , It suppresses the heat shrinkage of the carcass cord during vulcanization molding, and prevents the inner liner layer from penetrating between the carcass cords. Therefore,
It is possible to reduce the weight of the tire without lowering the tire durability or causing air leakage due to the biting of the inner liner layer between the carcass cords.

[Brief description of drawings]

FIG. 1 is a half sectional view showing an example of a pneumatic radial tire of the present invention.

FIG. 2 is a partial cross-sectional view of a tire inner side portion before vulcanization.

FIG. 3 is a partial cross-sectional view showing a change in a tire inner portion after vulcanization.

[Explanation of symbols]

1 Carcass layer 1c Carcass cord 2 Thai rubber layer 3 Inner liner layer

Claims (1)

[Claims] 1. In a pneumatic tire having an inner liner layer arranged inside a carcass layer, the dimension of the carcass layer from the carcass cord to the inner liner layer is 0.1 to 0.6 mm, and the carcass cord is
The heat shrinkage at 140 ° C is 0 to 1.0%, the heat shrinkage at 140 ° C is 0.11 g / d or less, and the intermediate elongation at room temperature is 2.25 g / D is 4.0% or more. Pneumatic tire made of polyester cord.